When setting or calibrating the suspension of a vehicle, such as a motorcycle or all-terrain vehicle, it is most desirable to measure the amount the front and rear suspension sags while the operator is mounted on the vehicle in a normal seated position. This step is critical for proper handling under racing or competition conditions.
Traditionally, properly and accurately measuring the suspension sag requires an assistant or helper to measure the sag while the operator is seated on the vehicle in a normal riding position. A common practice for measuring suspension sag is as follows. With the vehicle at rest under its own resting weight, the assistant first measures the distance between a first point on the vehicle's wheel (i.e. a wheel hub) and a second point on the vehicle's body (i.e., a fender). Then, with the operator mounted on the vehicle in a riding position, a second measurement is taken between the two previously established points. The difference between the two measurements would be the calculated sag of the vehicle under riding conditions from which a suspension adjustment would be made to optimize vehicle handling.
However, when an assistant who can take this measurement is not available, this practice cannot be administered. Thus, other systems have been devised which at least allow for solo measurement by an operator. One system for solo measurement of suspension sag generally uses a measuring element mounted onto the vehicle. While sitting in the vehicle, the operator must set the measuring element by reaching toward the measuring device. This movement shifts the operator out of a normal riding position and results in an inaccurate measurement because of the shifted weight. To alleviate this problem, slider systems have been used that include a sliding element (having measurement gradations thereon) that is mounted within a static tube. A measuring ring is frictionally secured on the sliding element. The sliding element slides within the static tube as the weight of the operator is added to the vehicle. The measuring ring memorializes the degree of movement once the weight has been removed. Thus, the operator can read the gradation on the sliding element adjacent the measuring ring once the operator has dismounted the vehicle, to determine the amount of suspension sag. This system, however, suffers from a number of drawbacks such as general difficulty in using, inaccuracy due to the sliding element or measuring ring moving beyond its position after the operator dismounts the vehicle, user error in reading the gradation or in calculating the measured distances and the inability to check instantaneous sag while the operator is mounted on the vehicle.
What is needed in the art is a device and system for measuring the sag of a vehicle's suspension that can quickly and accurately measure sag distance when used solely by an operator without use of an assistant and precisely while the operator is seated in a normal operating position.